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Similar, But Different Genomes Separate Mountain Bees From Savannah Bees In Africa

Similar, But Different Genomes Separate Mountain Bees From Savannah Bees In Africa

Posted by
Bee Culture
on June 02, 2017

Mountain-dwelling East African honey bees have distinct genetic
variations compared to their savannah relatives that likely help them to
survive at high altitudes.

And the bees living in the mountain forests look and behave differently from their surrounding lowland counterparts,

Mountain bees are larger, darker and less aggressive than savannah
bees, and can fly at lower temperatures and conserve honey when flowers
aren’t blooming

But despite their differences, the bees are the same sub-species.

To understand the genetic basis for these high-altitude
adaptations, researchers from the University of Hohenheim in Germany and
Uppsala University in Sweden sequenced the genomes of 39 bees from two
highland and two lowland populations in Kenya.

They report the genomes of all the populations are highly similar,
but two regions located on chromosome 7 and 9 show consistent
differences between bees living in high and low-altitude environments.

The segment on chromosome 7 contains e.g. receptor genes for a
neurotransmitter called octopamine, which plays a role in learning and
foraging. The clear divergence of these two genetic variations suggests
that they have an ancient origin and likely existed in bee populations
before the groups spread their mountain and savannah habitats.

The new study of the genomes of high-altitude honey bees in Kenya
reveals novel insights into their evolutionary history and the genetic
basis of local adaptation.

Scientists had thought that mountain and savannah populations were
each distinct sub-species. The high degree of similarity in their
genomes, as revealed in the current study, shows that they constantly
interbreed.

The highly diverged segments likely represent structural
rearrangements, such as inversions, in which the exchange of genetic
material is suppressed. Previous studies have identified octopamine as
an important signaling molecule in other insects living in low
temperature and low oxygen conditions.

“Our findings complement several other landmark studies – for
example in Heliconius butterflies and Solenopsis ants – where
adaptations have been similarly tied to structural variants or
supergenes,” says University of Hohenheim researcher Martin Hasselmann.

But the phenomenon has never been previously documented in honey bees, the researchers report in the journal PLOS Genetics.

“Our results should therefore spur further research into the role
of supergenes in environmental adaptation,” Hasselmann says.

“We are planning now to measure the distribution of these
divergent segments in other geographic locations and to elucidate the
functional link of these genes with behavior.”